1. Field of the Invention
This invention relates to a brake oil pressure controlling valve device for vehicles in which oil pressure supplied for actuating a rear wheel brake is made to be reduced to a level lower than that of oil pressure for actuating a front wheel brake.
2. Description of the Prior Art
There is known a brake oil pressure controlling valve device of the kind which is constructed as follows. A valve housing is interposed in an oil path connecting an output port of a master cylinder and the rear wheel brake, and the valve housing is provided therein with a reducing valve which can proportionally reduce output oil pressure from the output port to transmit the reduced oil pressure to the rear wheel brake, and with a pressure adjusting spring which urges the reducing valve in the valve opening direction for determining the reduction starting pressure thereof. According to such a brake oil pressure controlling valve device, when braking input larger than a predetermined value is applied, the front wheel brake is adapted to be actuated with relatively high pressure, which front wheel brake is disposed on the side of the vehicle body where the downward load of the body is increased upon braking, while the rear wheel brake which is disposed on the side of the vehicle body where the downward load is decreased upon braking is adapted to be actuated with relatively low pressure. Thus, there is obtained such an advantage that brake can be applied with good efficiency.
However, even with use of a brake oil pressure controlling valve device of the mentioned type, the rear wheel may be brought into a locked state to lower brake efficiency when braking input is too large or when condition of the road surface is bad.